The present invention relates to a chain and flight conveyor for use in conveying materials in the mining industry, and, in particular, to an improved design of a chain and flight conveyor. Still more particularly, this invention relates to conveyor chains for continuous miners and chain haulage units.
Conveyor flights with various coatings have been attempted in the past. The primary reason for these coatings was for noise control. While the coatings have been shown to reduce conveyor noise by 5-10 dBA, these materials wore off of the flights relatively quickly and were determined not to be of sufficient value for commercial use on continuous miners or longwall equipment. The coatings compressed beyond their working limit and began to tear and chuck out. One of the reasons for this failure is that the coating was too thin. There is a limited amount of space available on the conveyor for the flight bars, so in order to make the coating thicker, the integrity of the existing flight is compromised.
Urethane coating on conveyor chain flights has proven effective in reducing the noise exposure of continuous miner operators. The problems preventing widespread acceptance of this solution are the cost of implementation and maintenance of the chain, and the durability of the urethane coating.
The most successful urethane-coated flight design to date is a standard forged steel conveyor flight, which is machined down to reduce its thickness and thus allow room for the urethane coating. The machined-down flight is then used as a flight core, which is encapsulated in the urethane coating. But the coating is thinner than desired, and the corners of the steel flight cause stress concentration on the urethane coating. The end of the flight nearest the chain is currently enlarged and has holes to fit the chain pins. The urethane coating is undesirably thin due to the enlarged end of the flight.
The flight core is welded integral to the chain flight section, which is a part of the chain assembly. Replacing a flight due to loss of the urethane coating is expensive and difficult. If more than a few flights have lost their urethane coating, it is uneconomical to repair the chain, and the entire chain must be replaced.